BARKATULLAH UNIVERSITY BHOPAL

ORGANIZATION AND CHARACTERSTICS OF VIRUSES
BARKATULLAH UNIVERSITY BHOPAL
PRESENTED BY
MUHAMMAD ASIF KANTH
SUBMITTED TO :-
DEPARTMENT OF ZOOLOGY AND APPLIED AQUACULTURE
M.SC IV SEM
POWER POINT PRESENTATION

VIRUS is either DNA or RNA, that is protected by a protein coat called a CAPSID.
Viruses:A
are noncellular or Acellular
infectious agents
Virology:
study of viruses
Virologists:
scientists who study viruses
VIRUS:

General features of Viruses
Viruses are infectious agents with both living and nonliving characteristics.
1. Living characteristics of viruses
a. They reproduce at a fantastic rate, but only in living host cells.
b. They can mutate.

…General features of Viruses
2. Nonliving characteristics of viruses
They are acellular, that is, they contain no cytoplasm or cellular organelles.
They carry out no metabolism on their own and must replicate using the host cell's metabolic machinery.

GENERAL FEATURES OF VIRUSES
Virus particles contains either DNA or RNA (not both)
Nucleic Acid is surrounded or coated by a protein shell (capsid)
Some viruses possess a membrane-like envelope surrounding the particle

…General Properties of viruses
Consists of ?1 molecule of DNA or RNA enclosed in coat of protein
May have additional layers
Cannot reproduce independent of living cells nor carry out cell division as procaryotes and eucaryotes do
An intact viral particle is called a virion.

Viruses Can Help Cells, Too
Since viruses can transport DNA and RNA into cells, scientists are exploring Gene Therapy
In Gene Therapy, viral genetic material is replaced with new DNA
In time, this could be used to cure genetic diseases. Currently we have no cure for these types of illnesses

The Structure of Viruses
Virion size range is ~10-400 nm
All virions contain a nucleocapsid which is composed of nucleic acid (DNA or RNA) and a protein coat (capsid)
Some viruses consist only of a nucleocapsid, others have additional components
Envelopes
virions having envelopes = enveloped viruses
virions lacking envelopes = naked viruses

VIRAL ENVELOPES
Many viruses that infect humans and other animals are enveloped.
Envelopes form when viral glycoproteins and oligosaccharides associate with the plasma membrane of the host cell.
All envelopes have a phospholipid bilayer.

The End! And Review
Viruses are very simple: a shell containing either DNA or RNA.
They infect by hijacking cells’ machinery to force them to make more viruses.
Viruses are tiny, even compared to a cell.
Some viruses may prove useful in gene therapy as natural carriers of DNA that was specially designed to be good for a particular reason.